A field of the invention is signal conversion. The invention is directed to the digitization of analog signals.
Conversion of analog signals into digital signals is a fundamental task necessary in uncountable varieties of electronic devices. Conventional analog to digital converters (ADCs) employ electronic circuitry and repetitive processing to define the digital value of an analog signal. Higher frequency signals require higher sampling rates, i.e., the rate at which an analog signal is measured for the purpose of determining a corresponding digital value. One guideline is known as the Nyquist criteria. The Nyquist criteria requires that the digital sampling rate be greater than two times the analog frequency in order to faithfully reproduce the analog signal from the digital values. In practice, the sampling rate is typically chosen to be 5 times the analog frequency to be sampled. As frequencies of interest become high, e.g., in the tens of GigaHertz, conventional electronic techniques may not meet a desired rate of sampling. Even at lower frequencies, the electronics for a high quality analog to digital conversion may become complex and expensive.
In the invention, an analog signal is converted to an optical deflection. Conversion may be conducted at the rate of change permitted by the lower of the speed of deflection or rate of optical pulses delivered to the deflector. In preferred embodiments, an N-bit parallel output is obtained. A particularly preferred embodiment patterns the light beam with a spatial filter into an N-bit binary light pattern that is then collected and sensed by optical detectors.